The PX259 Prime supports HDR10 signals, but we’d place it in the category of monitors that merely process HDR signals without significantly improving the image. It doesn’t have a dynamic contrast feature or enough dynamic range to do the standard justice. Additionally, you have to manually switch modes each time. In some games, we saw a slight improvement, but in others, the image looked the same as SDR.
HDR Brightness and Contrast
The PX259 Prime delivers the same peak brightness, black levels and contrast in HDR mode as it does in SDR. But some HDR content looks slightly better, thanks to the enhanced tone map, which is very accurately rendered. There is a dynamic contrast option in the OSD, but it doesn’t affect contrast and only adds edge enhancement. The other monitors all peak over 400 nits, and the top two screens have far more contrast because of their dynamic features that lower black levels.
Grayscale, EOTF and Color
Since the PX259 Prime allows calibration in HDR mode, we gave it a try. The only caveat is the RGB settings are shared by SDR and HDR in the same picture mode. To get around this, use one of the Game mode memories to save independent configurations. By default, with color temp set to Warm, HDR grayscale is cool with blue errors that rise to the tone map transition at 60% brightness. Adjusting the RGB sliders fixes this error without affecting the EOTF, which tracks very close to spec.
Calibration also has a positive effect on color saturation. Though limited to sRGB, the PX259 Prime delivers extra punch with solid HDR color rendering. Hue errors are minor. Cyan is slightly blue, and magenta is also a little cool. These are minor issues. Overall, HDR color accuracy is as good as what we found in SDR mode. And HDR looks slightly better than SDR when comparing the same games side by side.